Population growth is only part of our ecological problem

Population growth is a complex issue that is only partly responsible for this crisis — the solution is not just a matter of family planning.

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There is a famous ‘equation’ proposed by Paul Erlich and John Holdren in 1972: I (human impact on the Earth) = P (population) x A (level of affluence, usually measured by GDP per person) x T (technology). While affluence is not quite the same as material consumption, land damage and pollution production (all key indicators of impact on the Earth), it is not a bad proxy; as we get wealthier, we consume more stuff and produce more waste.

The point is simple; it’s not just how big the population is, but how much each person consumes – and our technology can either make things worse, because we become more powerful and more damaging, or make things better if we become more efficient.

"We need to both reduce population and reduce consumption per person."

The latest World Bank data tracking changes since 1960 shows that between 1960 and 2017 global population grew from 3.03 to 7.53 billion, or almost 2.5 times. In that same period, GDP per person grew from $3,694 to $10,634, measured in constant 2010 US dollars (which adjusts for inflation), or almost 3 times. Put these two together and humanity’s impact has grown more than seven-fold in these 67 years.

It is illuminating to compare Canada on those same metrics. Between 1960 and 2017 Canada’s population increased just over two times and the GDP per person increased just over three times, so our impact on the Earth increased more than six times over those 67 years, measured this way. But on top of that, our per person impact is much higher than the global average – and greater than the Earth can sustain - so further increases in our already excessive footprint will be far more damaging than increases in the GDP and ecological footprint of low and middle-income countries.

The Global Footprint Network has just released its latest data. Overall, the global footprint for humanity in 2014 was equivalent to 1.7 Earth’s worth of biocapacity. If everyone in the world lived the way we do in Canada, we would need 4.8 Earths. So we live at almost three times the global average, meaning a child born in Canada will have roughly three times the impact on the Earth of an average child – and six times the impact of a child born in a lower middle-income country .

Thus we need to both reduce population and reduce consumption per person. But from a global impact perspective, reducing both these factors in high-income countries such as Canada will have a far greater beneficial effect than doing so in low-income countries. So attempts by some high-income countries to increase population size - and a 2017 article in The Independent newspaper in the UK identifies ten countries that are doing so - are very misguided.

Moreover, we have good evidence dating back decades that one of the most important ways to reduce population size is through education – particularly for women. In a 2015 interview with the World Economic Forum, Wolfgang Lutz - founding director of the Wittgenstein Centre for Demography and Global Human Capital and lead author of World Population and Human Capital in the 21st Century – noted “Education leads to lower birth rates and slows population growth”. He also linked education to poverty eradication, economic growth and environmental consciousness.

But universal education is expensive, and requires sufficient economic development to create enough wealth to achieve it. (It also requires enlightened leaders and policies that prioritise universal education, especially for girls and young women.)

So in summary, from the point of view of global impact on the planet, the key priority is to reduce the size of both the population and the ecological footprint per person of high-income countries. But for low-income countries, we need to support their economic development (while helping to ensure it follows a 21st century sustainable development path, not a 19th/20th century industrial development path) and support the creation of universal education, especially for young women, contributing to their emancipation.